package token;

import file.FilePosition;
import util.Characters;

import static java.lang.Character.isDigit;

public class TokenFactoryImpl implements TokenFactory {

    @Override
    public Token createToken(String text, FilePosition position) {
        if (text.length() == 0)
            throw new EmptyTokenTextException(position);

        char firstCharacter = text.charAt(0);

        switch (firstCharacter) {
            case Characters.LEFT_PARENTHESIS:
                return new LeftParenthesis(text, position);
            case Characters.RIGHT_PARENTHESIS:
                return new RightParenthesis(text, position);
            case Characters.SINGLE_QUOTE:
                return new QuoteMark(text, position);
            case Characters.DOUBLE_QUOTE:
                return new QuotedString(text, position);
            case Characters.BACKQUOTE:
                return new Backquote(text, position);
            case Characters.AT_SIGN:
                return new AtSign(text, position);
            case Characters.COMMA:
                return new Comma(text, position);
            default:
                if (isNumeric(firstCharacter, text))
                    return new Number(text, position);
                else if (Characters.INSTANCE.isLegalIdentifierCharacter(firstCharacter))
                    return new Identifier(text, position);
        }

        throw new BadCharacterException(text, position);
    }

    private boolean isNumeric(char firstCharacter, String text) {
        return isDigit(firstCharacter) || isPrefixedNumeric(firstCharacter, text);
    }

    private boolean isPrefixedNumeric(char firstCharacter, String text) {
        return Characters.INSTANCE.isNumberPrefix(firstCharacter) && isNextCharacterDigit(text);
    }

    private boolean isNextCharacterDigit(String text) {
        return (text.length() > 1) && isDigit(text.charAt(1));
    }

    @Override
    public Token createEofToken(FilePosition position) {
        return new Eof("EOF", position);
    }
}